----- Original Message -----
> From: "Kevin Wolf" <kw...@redhat.com>
> To: "Paolo Bonzini" <pbonz...@redhat.com>
> Cc: qemu-devel@nongnu.org, stefa...@redhat.com, ebl...@redhat.com,
> p...@kamp.de
> Sent: Wednesday, July 31, 2013 11:21:27 AM
> Subject: Re: [PATCH v3 19/19] block: look for zero blocks in bs->file
>
> Am 25.07.2013 um 16:23 hat Paolo Bonzini geschrieben:
> > Reviewed-by: Eric Blake <ebl...@redhat.com>
> > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> > ---
> > block.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/block.c b/block.c
> > index 8738937..1493f22 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -2991,7 +2991,7 @@ static int64_t coroutine_fn
> > bdrv_co_get_block_status(BlockDriverState *bs,
> > int nb_sectors, int
> > *pnum)
> > {
> > int64_t n;
> > - int64_t ret;
> > + int64_t ret, ret2;
> >
> > if (sector_num >= bs->total_sectors) {
> > *pnum = 0;
> > @@ -3017,6 +3017,14 @@ static int64_t coroutine_fn
> > bdrv_co_get_block_status(BlockDriverState *bs,
> > ret |= BDRV_BLOCK_ZERO;
> > }
> >
> > + if (bs->file &&
> > + (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> > + (ret & BDRV_BLOCK_OFFSET_VALID)) {
> > + ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
> > + *pnum, pnum);
>
> Here the error check is missing, too.
Right. Here I can ignore errors, but I should still check ret2 >= 0 before
taking random bits out of it.
Paolo
>
> > + ret |= (ret2 & BDRV_BLOCK_ZERO);
> > + }
> > +
> > return ret;
> > }
>
> Kevin
>
